(flow off gradually; "The rain water drains into this big vat")
(deplete of resources; "The exercise class drains me of energy")
(empty of liquid; drain the liquid from; "We drained the oil tank")
(make weak; "Life in the camp drained him")
(emptied or exhausted of (as by drawing off e.g. water or other liquid); "a drained marsh"; "a drained tank"; "a drained and apathetic old man...not caring any longer about anything")
(very tired)
(drained of electric charge; discharged; "a dead battery"; "left the lights on and came back to find the battery drained")